The quality of end user experience in Wireless Networks is of great importance for the Network Operators because it is one of the elements that attracts and keeps subscribers and builds customer loyalty. For that reason, all wireless network operators track the network performance indicators and demand from the infrastructure and mobile vendors that certain performance criteria are met to satisfy a level of quality of the end user experience. The various metrics measuring the performance of the network are generally called Key Performance Indicators (KPI).
For tracking reasons, the KPIs can be grouped under three separate categories.
The first types of indicators are the ones tracking the availability or continuity of end user services, such as, success rates or retainability rates.
The second type of indicators track the response time in establishing services for the end user. These are termed as Signaling Plane Delay KPIs.
The third type is specific for data traffic to monitor round trip delay and throughput of the established Radio Access Bearer (RAB). These KPIs are termed as Data Path KPIs.
Even though it is feasible to measure the total data path latency for any given user and for any given service, it is in current practice prohibitively expensive to measure the apportionment of this total delay, since many network elements, end user equipments and transport network elements contribute to this delay. When an end-to-end data path delay is within an expected range, knowledge of specific element latencies are of academic interest with a possible use of longer term optimization of network element latencies. When the measured end-to-end latency is higher than the expected value, it is a matter of urgency to know which of the network elements are the causes of this extra delay.
FIG. 1 illustrates a simplified UMTS (Universal Mobile Telecommunications System) network 100, having network elements Radio Network Controller (RNC) 102, Serving GPRS Support Node (SGSN) 104, NodeB (base station transceiver) 106, and User Equipment (UE) 108, all supervised by a Network Monitoring system 110. Physical connections are represented by solid lines between network elements, and application layer connections are represented by dashed lines between network elements. Network Protocol Analyzers 112A, 112B, 112C are installed at the interfaces between these nodes in order to capture message packets and log the time at which they are captured. In operational telecommunications networks with hundreds of nodes and thousands of users, the scaling of this approach becomes very impractical. In addition, this approach presumes that the Network Protocol Analyzers can decode the captured packets so as to associate a time stamp with a particular user and/or service. This presumption becomes problematic if the packets are encrypted.
Therefore, it would be desirable to have a method or apparatus capable of measuring round trip delay and apportioning latency among network elements contributing to the round trip delay without the drawbacks of present methods.